■ Abstract : Membranes have been used throughout history to purify water. Advances made in membrane technologies over the past century have typically focused on either enhancing the separation efficiency of a membrane or improving the permeation flux. Enhancing the separation efficiency, however, inevitably leads to a reduction in the permeation flux, while improving the permeation flux results in lower separation efficiencies. There have been attempts to employ highly porous three-dimensional inverse opal (3D-IO) structures as a means to develop high-performance isoporous membranes. In particular, 3D-IO structures can be implemented to impart advanced membrane properties through secondary processes of multiscale-architecturing, such as elaborate control over the interconnected pore size, embedding specific functional moieties, and incorporating structural hierarchy; this eventually creates high performance membrane properties that attain both high separation efficiencies and high permeabilities.